For my own use the radius arm design looks like the simplest solution. I'm not looking for 16" of wheel travel, though I do drive semi-fast in the desert. The added complexity of a simple, non-laterally locating 3 link to get a mild increase in control over the Castor angle doesn't look like it is worth it to me. For others I can see some advantages.
One great advantage of to the radius is the lower amount of nose dive under hard breaking. Which is great for speed but not for crawling, a lower amount of brake dive helps in eliminating "Torque" loading of the axle while crawling. Anyone ever notice that lots of rigs that are linked and have a high Anti Dive or Anti Squat (same thing) in front tend to raise up when torque is applied through the axle. A lower Anti Dive will help eliminate a lot of that, and for crawling up step stuff that is a huge advantage not having your suspension push your nose up.
Im not trying to make enemies just trying to make a clear point. I dont disagree with most of what you said, maybe the bushing thing buts that about it.
